This invention relates to a solid-state imaging (image pick-up) device and a method of manufacturing the same, and more particularly to a solid-state imaging device of the structure comprising color filter and a dyeing layer process in a color filter production process suitable when applied thereto.
The configuration of a conventional solid-state imaging device will now be described with reference to FIGS. 3-5. As shown in FIG. 3, this solid-state imaging device comprises: groups of pixels 51 to 53 two-dimensionally arranged on a semiconductor substrate; vertical CCD shift registers 54 to 56 respectively disposed between these groups of pixels 51 to 53, and adapted for transferring, in a vertical direction, signal charges produced in the pixels after undergone photoelectric conversion and stored therein; a horizontal CCD register 57 adjacently disposed at the lower end portion of the vertical CCD shift registers 54 to 56, and adapted for reading out, in a horizontal direction, signal charges of the vertical CCD shift registers 54 to 56, and an output circuit 58 disposed at the terminating end of the horizontal CCD shift register 57.
This solid-state imaging device is manufactured as follows. Initially, an insulating film 62 is formed on a semiconductor substrate 61 so as to include transfer electrodes 63, 64 (see FIG. 4C) of the vertical CCD shift registers 54 to 56 to form light shielding films 65 on the insulating film 62 so that they are positioned immediately above the transfer electrodes 63, 64 thereafter to form a protective film 66 so as to cover the light shielding films 65. Then, a first color filter pattern 67 is formed on the protective film 66. In this case, the first color filter pattern 67 is formed by coating resist for color filter onto the protective film 66 to carry out mask pattern transfer at a predetermined position with respect to the light shielding films 65 to implement the development processing thereto (FIG. 4A).
Thereafter, similar process is carried out for a second time to respectively form a second color filter pattern 68 (FIG. 4B) and a third color filter pattern 69 (FIG. 4C).
However, with the such conventional manufacturing method, the problem that the color picture characteristic is degraded took place.
Namely, there were instances where, as shown in FIG. 5A, e.g., the first color filter pattern 67 is positionally shifted to the left side with respect to the light shielding film 65 so that gap takes place between the first color filter pattern 67 and the light shielding film 65 of the right side. In such a case, any shift (difference from the ideal characteristic) takes place in the spectral characteristic by the dyeing (coloring) pattern of the first color filter pattern 67. For this reason, unsatisfactory color reproducibility takes place, thus degrading the color picture characteristic to much degree.
Moreover, in a state as described above, as shown in FIG. 5B, there are instances where the third color filter pattern 69 takes a form riding onto the first color filter pattern 67 as indicated by color filter pattern 69xe2x80x2 although it is not admitted into the adjacent pixel region. As a result, thick portions locally take place. Thus, any shift would similarly takes place in the spectral characteristic of the first color filter pattern 67.
Further, with miniaturization of the device, the width of the light shielding film 65 between pixels becomes smaller. As a result, with the prior art, the problem that process margin cannot be taken place.
This invention has been made in view of the problems with the prior art, and its object is to provide a solid-state imaging device of the structure comprising color filter, and a color filter formation process suitable when applied thereto, in which the pattern end portion position of the color filter pattern is determined by the self-alignment with respect to the light shielding film so that the process margin with respect to the color reproducibility is increased.
A solid-state imaging device of this invention comprises: a semiconductor substrate, light shielding films formed so as to define light opening portions by a material of light shielding characteristic above the semiconductor substrate; and color filter layers formed above the light shielding films, and such that they are caused to correspond to the light opening portions and respective end portions thereof are positioned within regions corresponding to regions where the light shielding films are respectively formed.
Transfer electrodes are preferably respectively provided below the light shielding films in a more practical sense.
One of the color filter layers is preferably formed on a certain region where the light shielding film is formed in the state where a gap is held between the end portion thereof and that of the other color filter layer adjacent thereto.
Moreover, a method of manufacturing a solid-state imaging device of this invention comprises the steps of: forming a first insulating film on a semiconductor substrate; allowing a material of light shielding characteristic to selectively remain within regions where light shielding films are to be respectively formed on the fist insulating film to form the light shielding films; forming a second insulating film in this state; selectively forming a color filter layer on the second insulating film so as to cover an opening portion surrounded by the light shielding films and to allow respective end portions thereof to he positioned on the regions where the light shielding films are respectively formed.
Formation of the color filter layer is repeatedly carried out with respect to plural colors.
It is desirable to set light irradiation quantity so that the remaining film ratio (percentage) of the portion positioned on the light shielding film of resist constituting the color filter layer is lower than the remaining film ratio (percentage) of the portion positioned on the light opening portion.